13,961 research outputs found
Applications of Wavelets to the Analysis of Cosmic Microwave Background Maps
We consider wavelets as a tool to perform a variety of tasks in the context
of analyzing cosmic microwave background (CMB) maps. Using Spherical Haar
Wavelets we define a position and angular-scale-dependent measure of power that
can be used to assess the existence of spatial structure. We apply planar
Daubechies wavelets for the identification and removal of points sources from
small sections of sky maps. Our technique can successfully identify virtually
all point sources which are above 3 sigma and more than 80% of those above 1
sigma. We discuss the trade-offs between the levels of correct and false
detections. We denoise and compress a 100,000 pixel CMB map by a factor of
about 10 in 5 seconds achieving a noise reduction of about 35%. In contrast to
Wiener filtering the compression process is model independent and very fast. We
discuss the usefulness of wavelets for power spectrum and cosmological
parameter estimation. We conclude that at present wavelet functions are most
suitable for identifying localized sources.Comment: 10 pages, 6 figures. Submitted to MNRA
Results of a low power ice protection system test and a new method of imaging data analysis
Tests were conducted on a BF Goodrich De-Icing System's Pneumatic Impulse Ice Protection (PIIP) system in the NASA Lewis Icing Research Tunnel (IRT). Characterization studies were done on shed ice particle size by changing the input pressure and cycling time of the PIIP de-icer. The shed ice particle size was quantified using a newly developed image software package. The tests were conducted on a 1.83 m (6 ft) span, 0.53 m (221 in) chord NACA 0012 airfoil operated at a 4 degree angle of attack. The IRT test conditions were a -6.7 C (20 F) glaze ice, and a -20 C (-4 F) rime ice. The ice shedding events were recorded with a high speed video system. A detailed description of the image processing package and the results generated from this analytical tool are presented
Advanced ice protection systems test in the NASA Lewis icing research tunnel
Tests of eight different deicing systems based on variations of three different technologies were conducted in the NASA Lewis Research Center Icing Research Tunnel (IRT) in June and July 1990. The systems used pneumatic, eddy current repulsive, and electro-expulsive means to shed ice. The tests were conducted on a 1.83 m span, 0.53 m chord NACA 0012 airfoil operated at a 4 degree angle of attack. The models were tested at two temperatures: a glaze condition at minus 3.9 C and a rime condition at minus 17.2 C. The systems were tested through a range of icing spray times and cycling rates. Characterization of the deicers was accomplished by monitoring power consumption, ice shed particle size, and residual ice. High speed video motion analysis was performed to quantify ice particle size
Probing the Primordial Power Spectrum with Cluster Number Counts
We investigate how well galaxy cluster number counts can constrain the
primordial power spectrum. Measurements of the primary anisotropies in the
cosmic microwave background (CMB) may be limited, by the presence of
foregrounds from secondary sources, to probing the primordial power spectrum at
wave numbers less than about 0.30 h Mpc^{-1}. We break up the primordial power
spectrum into a number of nodes and interpolate linearly between each node.
This allows us to show that cluster number counts could then extend the
constraints on the form of the primordial power spectrum up to wave numbers of
about 0.45 h Mpc^{-1}. We estimate combinations of constraints from PLANCK and
SPT primary CMB and their respective SZ surveys. We find that their
constraining ability is limited by uncertainties in the mass scaling relations.
We also estimate the constraint from clusters detected from a SNAP like
gravitational lensing survey. As there is an unambiguous and simple
relationship between the filtered shear of the lensing survey and the cluster
mass, it may be possible to obtain much tighter constraints on the primordial
power spectrum in this case.Comment: Clarifications added and a few minor corrections made. Matches
version to appear in PR
Current cosmological constraints from a 10 parameter CMB analysis
We compute the constraints on a ``standard'' 10 parameter cold dark matter
(CDM) model from the most recent CMB and data and other observations, exploring
30 million discrete models and two continuous parameters. Our parameters are
the densities of CDM, baryons, neutrinos, vacuum energy and curvature, the
reionization optical depth, and the normalization and tilt for both scalar and
tensor fluctuations.
Our strongest constraints are on spatial curvature, -0.24 < Omega_k < 0.38,
and CDM density, h^2 Omega_cdm <0.3, both at 95%. Including SN 1a constraints
gives a positive cosmological constant at high significance.
We explore the robustness of our results to various assumptions. We find that
three different data subsets give qualitatively consistent constraints. Some of
the technical issues that have the largest impact are the inclusion of
calibration errors, closed models, gravity waves, reionization, nucleosynthesis
constraints and 10-dimensional likelihood interpolation.Comment: Replaced to match published ApJ version. More details added. 13 ApJ
pages. CMB movies and color figs at
http://www.hep.upenn.edu/~max/10par_frames.html or from [email protected]
Long-Term Nitrogen and Phosphorus Fertilization of Irrigated Grain Sorghum
Long-term research shows that phosphorus (P) and nitrogen (N) fertilizer must be applied to optimize production of irrigated grain sorghum in western Kansas. In 2014, N applied alone increased yields 49 bu/a, whereas N and P applied together increased yields up to 81 bu/a. Averaged across the past 10 years, N and P fertilization increased sorghum yields up to 73 bu/a. Application of 40 lb/a N (with P) was sufficient to produce more than 80% of maximum yield in 2014, which almost equals the 10-year average. Application of potassium (K) has had no effect on sorghum yield throughout the study period
Long-Term Nitrogen and Phosphorus Fertilization of Irrigated Grain Sorghum
Long-term research shows that phosphorus (P) and nitrogen (N) fertilizer must be applied to optimize production of irrigated grain sorghum in western Kansas. In 2016, N applied alone increased yields 71 bu/a, whereas N and P applied together increased yields up to 93 bu/a. Averaged across the past 10 years, N and P fertilization increased sorghum yields up to 77 bu/a. Application of 80 lb/a N (with P) was sufficient to produce 89% of maximum yield in 2016 which is slightly less than the 10-yr average. Application of potassium (K) has had no effect on sorghum yield throughout the study period. Average grain N content reached a maximum of ~0.7 lb/bu while grain P content reached a maximum of 0.15 lb/bu (0.34 lb P2O5/bu) and grain K content reached a maximum of 0.19 lb/bu (0.23 lb K2O/bu). At the highest N, P, and K rate, apparent fertilizer recovery in the grain was 33% for N, 69% for P, and 40% for K
Long-Term Nitrogen and Phosphorus Fertilization of Irrigated Corn
Long-term research shows that phosphorus (P) and nitrogen (N) fertilizer must be applied to optimize production of irrigated corn in western Kansas. In 2015, N applied alone increased yields 70 bu/a, whereas P applied alone increased yields only 12 bu/a. Nitrogen and P applied together increased yields up to 129 bu/a. This is below the 10 year average, where N and P fertilization increased corn yields up to 144 bu/a. Application of 120 lb/a N (with P) produced about 98% of maximum yield in 2015, which is 5% more than the 10-year average. Application of 80 instead of 40 lb P2O5/a increased average yields only 1 bu/a. Average grain N content reached a maximum of 0.6 lb/bu while grain P content reached a maximum of 0.15 lb/bu (0.34 lb P2O5/bu)
Long-Term Nitrogen and Phosphorus Fertilization of Irrigated Corn
Long-term research shows that phosphorus (P) and nitrogen (N) fertilizer must be applied to optimize production of irrigated corn in western Kansas. In 2016, N applied alone increased yields 85 bu/a, whereas P applied alone increased yields only 12 bu/a. Nitrogen and P applied together increased yields up to 164 bu/a. This is 20 bu/a greater than the 10-year average, where N and P fertilization increased corn yields up to 144 bu/a. Application of 120 lb/a N (with highest P rate) produced about 94% of maximum yield in 2016, which is similar to the 10-year average. Application of 80 instead of 40 lb P2O5/a increased average yields 6 bu/a. Average grain N content reached a maximum of 0.6 lb/bu while grain P content reached a maximum of 0.15 lb/bu (0.34 lb P2O5/bu). At the highest N and P rate, AFNRg was 44% and AFPRg was 62%
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